Technically it's more like "curl -i" rather than "-I" since it does a GET request rather than a HEAD request. Which is a good thing as the former is more accurate. There are rare occasions when a web server might be sending wrong headers which get overwritten with the correct headers from the executing code (I think one of OVH's portals suffered from this issue - though that may have since been fixed)

You probably might want to stick "-s" in there too; silence the transfer statistics which curl (annoyingly) adds when output is piped / redirected.